NASA Technical Reports Server (NTRS) 20060050748: Use, Assessment, and Improvement of the Loci-CHEM CFD Code for Simulation of Combustion in a Single Element GO2/GH2 Injector and Chamber

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NASA Marshall Space fight Center
I
Use, Assessment, and Improvement of the Loci-CHEM CFD
Code for Simulation of Combustion in a Single Element
G02/GH2 Injector and Chamber
Douglas G. Westra, Ph,D.*,J eff Lin*, Jeffiey S. West, Ph.D.*, Paul K. TuckeT*
This paper documents a continuing effort at Marshall Space Flight Center (MSFC) to
use, assess, and continually improve CFD codes to the point of material utility in the design
of rocket engine combustion devices. This paper describes how the code is presently being
used to simulate combustion in a single element combustion chamber with shear coaxial
injectors using gaseous oxygen and gaseous hydrogen propellants. The ultimate purpose of
the efforts documented is to assess and further improve the Loci-CHEM code and the
implementation of it. Single element shear coaxial injectors were tested as part of the Staged
Combustion Injector Technology (SCIT) program, where detailed chamber wall heat fluxes
were measured. Data was taken over a range of chamber pressures for propellants injected
at both ambient and elevated temperatures. Several test cases are simulated as part of the
effort to demonstrate use of the Loci-CHEM CFD code and to enable us to make
improvements in the code as needed. The simulations presented also inlcude a grid
independence study on hybrid grids. Several two-equation eddy viscosity low Reynolds
number turbulence models are also evaluated as part of the study. All calculations are
presented with a comparison to the experimental data. Weaknesses of the code relative to
test data are discussed and continuing efforts to improve the code are presented.
*
NASNMarshall Space Flight Center
Mail Code ER43
MSFC, AL 35812
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Injector D MSFC Developed being Devices bCodes for in but independently being des are from developed parallel, and the in continually design are two of e codes used, improved rockustion devices 3 Loci-CHEM, version Density- based : Loci-Stream: Pressure-based (not discussed here) FDNS that has aReplacing (Finite Difference, Navier-Stokes), solver been used 15 years Chem: Finite-volume flow solver for generalized grids NSF part Developed at Mississippi State University in via NASA and funded efforts CHEM uses high resolution approximate Riemann solvers to solye finite-rote chemically reaCHEM arc presented in the user gu~de. Ref.4) turbulent (Details flows. (CFD) Density- based computational fluid dynamics algorithm Preliminary implementation of pn-conditioning is available and is used extensively here Preconditioning methods for a chemically reacting flows are presently in beta mod - Loci-CHEM. very important component in the continuing development of Several turbulence models are available: Three Two-Equation Models and a One-Model Transport Menter's Shear Stress Model (SST) - general purpose model that is reasonably effective at predicting flow scpa~tions (BSL) Baseline Menter's Model - k-a, k-s Blended model: near the wall, away from the wall (KW) k-a, Wilcox's model - k m non-physical sensitivity to the free-steam and values Spalart-Allmaraas one equation model - C C++ is Loci-CHEM comprised entirely of and code and supported all popular on is and compile Typically require first cell from wall y+ values from to 0.1. 1 5) is the Parallelism supplied by Loci framework (Ref. MPI exploits multi-threaded and libraries to provide parallel capability Loci-CHEM is quite scalable 90% 64 a proximately parallel efficiency on to CPUs on the axisymmetric simulations that tb effort.
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